Cyclopentadienyltrialkoxytitanium compounds of the general formula LTi(OR).sub.3, in which L can be cyclopentadienyl radical and R can be an alkyl or aryl radical, are described in the literature as starting components for catalyst systems for the stereospecific polymerization of styrene: EP-A-322 663, EP-A-559 108, WO 94/10216.
Some processes for the preparation of titanium compounds of the formula LTi(OR).sub.3, are described in the literature.
According to Chemical Abstracts (CA): 55: 6398g; CA: 22273c; CA: 68: 13138e, di- or trialkoxytitanium chlorides are reacted in an inert solvent with metallated cyclopentadienyl derivatives according to the following general reaction scheme: ##STR1## where L is a cyclopentadienyl derivative; M is Li, Na, or MgCl; R' is an alkyl or aryl radical; and a is 2 or 3.
This process has serious disadvantages, in that the compounds Cl.sub.4-a Ti(OR').sub.3 have to be prepared in a complex manner from TiCl.sub.4 and Ti(OR.sup.1).sub.4 and purified.
According to Wailes, Coutts, Weigold: Organometallic Chemistry of Titanium, Zirconium and Hafnium, Academic Press, New York and London, pages 34-39, cyclopentadienyltitanium trichloride are reacted in inert solvents with alcohols in the presence of tertiary amine according to the general equation ##STR2## in which R" are alkyl radicals and L and R' have the meaning given above.
If the reaction is carried out under suitable conditions, although good yields of the desired reaction product can be achieved, the amine hydrochloride arising as a voluminous precipitate causes considerable problems in carrying out the reaction and in separation and workup.
Furthermore, despite considerable excesses of R'OH and base, complete replacement of the chlorine for the OR' radical can hardly be achieved, so that the reaction products contain undesirable residual chlorine contents.
One object of the present invention is therefore to provide an industrially elegant, cost-effective process by which very largely chloride-free, that is completely substituted, end products can be prepared without the formation of interfering voluminous precipitates.